Application of Quality by Design in Process Development

Richard Francis, Francis Biopharma

The presentation examines the philosophy of Quality by Design.It explores this holistic approach to process development and compares to the old paradigm of process development.It is this approach that has led to expressions such as "The process is the product", which means change your process and you change your product.Then any change to process and hence product typically requires repeat of clinical studies to some degree with extensive characterisation / comparability and the need for real time stability data.This means significant time (1-2 years at least) to gain regulatory agency approval and cost to deliver a modified process.

QbD in contrast is a methodology driven by a systematic evaluation of the process and products' attributes in the development of a detailed understanding as to the functional relationship between the process and the product.This at a high level would be defined as the process and products' Critical Quality Attributes (CQA's).A key foundation for QbD is risk assessment and development of an understanding as to the process environment and its impact on the product.This approach then facilitates the maintenance of product quality throughout the product lifecycle by continued process verification within a continuum of a knowledge base of process and product properties.QbD utilizes the knowledge generated from small scale process models and factorial experimental design to map out the process parameters to allow for the definition of the process and the process control space.

From initial inception a QbD program can seem a daunting task, however the purpose of this presentation is to help understand the steps that need to be taken and the methodology that will allow for a systematic development program to be established.The bottom line in terms of QbD process development is to demonstrate a science risk based approach to define process capability and control strategies to consistently deliver a product meeting pre-defined quality attributes which is safe for its intended use.

Traditional chemical engineering technology based on stainless steel has been applied as a standard in manufacturing of biopharmaceuticals over the last 30 years.Increasing requirements in quality and process control combined with relatively low product titers have led to highly complex and expensive equipment and facility layouts.The construction and commissioning of a new facility can take between 5 to 7 years and cost more than 350 million Euros.

Since 15 years, significant efforts have been made to increase process productivity and to develop new manufacturing technologies permitting reduction of CAPEX and OPEX costs.Major developments of disposable technology during the last 10 years have resulted in the possibility to replace traditional stainless steel equipment.The combination of process productivity and new technologies has a significant impact on the strategy for development and manufacturing of biopharmaceuticals and the associated costs.

Upstream Channel

The ICH guideline Q8 Pharmaceutical Development (also referred to as “Quality by Design”, QbD) was developed by the ICH Expert Working Group in consultation with regulatory parties.It provides guidance to design a quality product and its manufacturing process to consistently deliver the intended performance of the product.With its recent approval it is now up to the industry to translate the guideline into a daily practice in Research & Development compliant with the QbD principles.

Abbott Biologicals is dedicated to the development, manufacture and marketing of Influenza vaccines.One of the main process development projects currently ongoing at Abbott Biologicals concerns the improvement of the MDCK cell culture-based influenza manufacturing process.

This presentation describes the use of QbD principles in the improvement of the upstream process of MDCK-based influenza manufacturing, as applied by Abbott Biologicals.As illustration a development study is discussed.In brief; the “Design of Experiments” methodology was applied to improve virus propagation yields.This resulted in the description of design spaces and identification of optimal conditions.The optimal conditions were further evaluated for their performance in the downstream process.

Finally, attention is given to the integration of QbD principles into the day-to-day Quality Assurance of the development projects.

Selecting cell lines and developing processes that are robust and meet the commercial demands of a market launch is a key factor for reducing timelines and resource burdens for biopharmaceutical organizations.Cell lines and processes in the past were initially selected and developed in uncontrolled environments that poorly modeled bioreactors (commercial method of production) and not until late in development were cells introduced into controlled bioreactor environments.

Developing processes uncontrolled has risks associated with it.Screening media, for example, uncontrolled in the past was based often on resource limitations (bioreactors, number of media formulations, cost) not on whether it was the best way to screen or develop commercial ready medias and processes.“Bioreactor” medias and feeds need to be developed not “Shake Flask” medias and feeds.

Today we have high-throughput tools such as the Micro-24 Microbioreactor that allow investigators to conduct bioreactor work earlier in the process and deliver their projects to the pilot plant and beyond while fulfilling Quality by Design initiatives.A media development example using high throughput bioreactors will be presented which will include scale-up data.The flexibility of the Micro-24 tool will also be discussed through examples that include clone selections, parameter optimization, and the use of it as a troubleshooting tool.Controlled “high-throughput” bioreactor systems allow rapid, very early stage process development which can contribute to shorter development timelines and lower development costs.

The requirement for increasing amounts of highly purified plasmid DNA for clinical trials implies the development of cGMP compliant large-scale production process.As developments in fermentation have pushed productivity to 1 g/L and above, the bottleneck has now moved to the downstream processing portion of plasmid manufacturing.

A platform cGMP manufacturing process has been optimised in order to fulfil this demand, yielding 100 g of purified plasmid per 350 L of fermentation broth.This optimisation includes improvements in both upstream and downstream processing steps.On the upstream side, the development of a multistage fed-batch strategy was implemented:a first stage for biomass production followed by a second stage for specific plasmid biosynthesis.This approach allows reproducible plasmid production yield of 1 g of pDNA per liter of fermentation broth.Downstream processing starts with the cell paste harvesting by discontinuous centrifugation but alternative methods including microfiltration technologies are currently under investigation.The extraction of pDNA is performed using a proprietary alkaline lysis method that has been designed for large-scale purpose.This method is based on a three-step continuous treatment of the cell paste and soft mixings to recover the lysate containing pDNA predominantly under its therapeutically efficient supercoiled form.Clarification of the lysate has been adapted according to the large volumes produced.After the centrifugation of the recovered lysate, which is performed all along the continuous process of lysis, the supernatant is clarified by depth filtration using Stax™ disposable capsules followed by a 0.2 µm filtration.Removal of remaining contaminants is carried out by tangential flow filtration (removal of proteins and low molecular weight RNA) followed by a single anion-exchange chromatographic step (removal of RNA and open-circle form of pDNA).Both purification steps have been adapted for high pDNA concentrations.Final bulk is then formulated in the required buffer by ultrafiltration / diafiltration and submitted to sterile filtration.

The presented manufacturing process, which uses only one chromatographic step, fulfils the specifications for a clinical-grade pDNA material:reproducible high quality, cost-effective yields and cGMP compliant.

A systematic approach for system design and operating parameter optimisation will be presented including characterisation of key feed stream characteristics using conventional TFF configurations, flux excursion assessments using single-pass excursion modules and concentration in single-pass mode using a Cadence module with optimal configuration.

The impact on process performance in terms of number of load cycles required and dynamic binding capacity of the Protein A capture step will be discussed.In addition the effect on key product quality attributes (process and product related impurities) and product recovery performance will also be discussed.

Adsorption chromatography is the predominant technique used in large-scale purification of biological products, with several traditional modalities being well established for many decades.The continuous increases of protein expression titers and bioreactor feedstock volumes have created new challenges to improve downstream purification processes.Ion exchange chromatography resins with increased dynamic binding capacities have been introduced over the last 5-10 years, reaching protein capture levels exceeding 100 mg/mL at very short residence times.

However, resin selectivity is at least as important as capacity for the successful design of a robust process, and has often been neglected due to perception as a time-consuming and cumbersome task.The introduction of high-throughput screening methods in 96 well microfilter plates with associated robotics and powerful analytical technologies has allowed process developers to have more latitude in resin selection options, at early stages of process development.

This presentation will highlight the importance of selectivity in two industry-scalable chromatography modes:ion exchange (using 颇尔’s novel Q and S HyperCel™ high-productivity resins) and mixed-mode (or multi-mode) chromatography (using 颇尔’s family of MEP, HEA and PPA HyperCel™ resins).Chromatography bead and ligand design, as well as examples of purification of monoclonal antibodies and other recombinant proteins, will be discussed.

A manufacturing process for production of a CHO derived monoclonal, recombinant IgG1 (product) was developed on basis of platform technologies for purification of monoclonal antibodies (mAbs).The DSP consisting of finally three chromatography based steps and two basic virus clearance steps was designed to purify the mAb at a culture volume of 250 L. This scale was selected to produce material for toxicological studies and later-on for manufacturing of clinical grade material for phase I under cGMP conditions.

With regard to the accepted level of impurities in mAb preparations a polishing step based on membrane chromatography was introduced into the DSP.This step was intended to remove impurities, mainly host cell DNA to reach an acceptable level for the drug substance.

Data will be presented for description of the DSP development and the implementation of the membrane adsorber.In addition the impurity profile recorded at different scales as well as data derived from a virus clearance study will be discussed.